1. Seal Leakage
Causes: The working environment of pad printing machines involves frequent contact with inks, thinners, and other organic solvents, which can cause swelling and accelerated aging of rubber seals such as piston rod seals and end-cover O-rings. In addition, long-term reciprocating motion leads to normal wear of the seals, resulting in compressed air leakage.
Symptoms: Reduced cylinder thrust leads to insufficient pad pressure, causing faded or misaligned print patterns. A noticeable hissing sound of escaping air can often be heard near the pneumatic lines.
Solutions: Use seals made of solvent-resistant materials such as NBR (nitrile rubber) or FKM (fluororubber). Regularly replace aged seals and take measures to prevent ink from entering the cylinder chamber.
2. Sticking or Failure to Actuate
Causes: Condensed water, oil contaminants, and particulates in the compressed air supply can enter the cylinder barrel, increasing friction. Ink and dust deposits on the piston rod surface can also create additional resistance. Wear of the guide bushing may cause coaxiality deviations, leading to rod jamming and, in severe cases, complete failure of cylinder movement.
Symptoms: Sluggish or intermittent cylinder motion, halting mid-stroke, or inability to push the pad head to complete the printing cycle.
Solutions: Install a high‑precision FRL (filter‑regulator‑lubricator) unit to remove impurities and moisture. Regularly clean the piston rod surface to remove ink and dirt buildup. Replace the guide bushing when wear exceeds tolerance limits.
3. Magnetic Detection Failure
Causes: Most pad printing cylinders use magnetic switches for position feedback. Common issues include shifting of the switch mounting position, degradation of the built‑in magnetic ring due to ink contamination or demagnetization, and aging of the switch itself from oil mist or electrical wear. Fluctuations in air supply pressure can also cause variations in the cylinder's stop position, affecting switch sensing.
Symptoms: The PLC does not receive the proper in‑position signal, interrupting the printing cycle, or the switch triggers prematurely or incorrectly, resulting in misaligned printing positions.
Solutions: Periodically clean the magnetic switch and the area around the magnetic ring. Calibrate the switch mounting position and replace any faulty switches. Stabilize the air supply pressure to ensure consistent piston positioning.
For replacement or repair scenarios involving non‑standard sizes or challenging operating conditions, we can provide precision custom‑machined components – such as seals, guide bushings, or magnetic rings – according to your drawings or sample parts. This ensures a perfect fit and extended service life for your pad printing cylinders.
